let a:string = 'xiaoming'
let b:numder = 22
const c:boolean = true
let d:any = 3123.231
console.log(d.toFixed(2))

let e:unknown = 32
if(typeof e === 'number'){
    console.log(e.toFixed(2))
}
let f:null = null
let g:undefined = undefined

function add1():void{
    console.log("342")
}
function add2():never{
    console.log("332")
    throw new Error("cw")
}

interface Person {
    age: number,
    name: string
}
let p1: Person = {
    age: 11,
    name: "aaa"
};
let p2:{name:string,age:number}={
    name:'bbb',
    age:34
}
console.log(p2)
console.log(p1)